JPS61169615A - Engine intake device - Google Patents

Abstract

PURPOSE:To improve the output and fuel consumption, in a system where a control valve closable under light load is arranged in heavy load intake path, by correcting the opening of the control valve with correspondence to the air/ fuel ratio thereby regulating the intake air flow speed, intake swirl, etc. with correspondence to variation of the air/fuel ratio. CONSTITUTION:Intake air paths 5, 6 for heavy load and light load are formed in the downstream of a throttle valve 4 in an intake path 3 and communicated through an intake valve 8 to the combustion chamber 2 upon confluence. The heavy load intake path 5 is formed with relatively large diameter while a control valve 9 closable under light load is arranged in the way. While the light load intake path 6 is formed with relatively small diameter to open the downstream end in tangential direction of cylinder 1. Here, the control valve 9 will control the opening through a control unit 12 with correspondence to the engine operating condition while correct the opening with correspondence to the air/fuel ratio to be detected through a lean sensor (air/fuel ratio detecting means) 16.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in an intake system for an engine having a low-load intake passage and a high-load intake passage equipped with a control valve.

(Prior art) Conventionally, a low-load intake passage and a high-load intake passage equipped with a control valve are formed, and when the load is low, the control valve is used to supply intake air from the low-load intake passage. According to
In addition to increasing the intake flow velocity, it also creates an intake swirl to improve combustion performance.At high loads, the control valve opens to supply intake air from both intake passages, reducing intake resistance and suppressing intake swirl. The engine that did this is known. In particular, in order to appropriately adjust intake air supply conditions such as intake flow rate and intake swirl in various operating conditions, for example, as shown in Japanese Patent Application Laid-Open No. 59-138723, operating conditions such as engine rotation speed and load, and control Signals related to the opening degree of the control valve, such as the differential pressure before and after the valve, are detected, and the detected value of the differential pressure, etc., is compared with a target value read out from the storage device and adapted to the operating condition, and the above-mentioned detection is performed. A device is also known in which the opening degree of a control valve is feedback-controlled so that the opening value becomes a target value.

By the way, in the conventional device as described above, the intake flow velocity, intake swirl, etc. are adjusted by controlling the opening degree of the control valve only depending on the operating condition, but the air-fuel mixture supplied to the engine The required intake flow velocity and strength of intake swirl also vary depending on the air-fuel ratio. In other words,
Originally, the air-fuel mixture was at the stoichiometric air-fuel ratio (14.5 to 15.0)
The combustion speed is at its maximum when the air-fuel ratio is at a certain temperature, and the combustion speed tends to slow down as the combustion speed deviates from the stoichiometric air-fuel ratio. desirable. However, the conventional device described above merely controls the opening degree of the IIJtll valve according to the operating state, so if the air-fuel ratio changes even under the same operating state, for example, the air-fuel mixture becomes lean after warm-up. Inspiratory flow rate, etc.
It was not possible to adjust intake swirl, etc.

(Objective of the Invention) In view of these circumstances, the present invention not only adjusts the intake flow rate and intake swirl according to the operating condition, but also adjusts the intake flow rate and intake swirl appropriately when the air-fuel ratio changes. The present invention provides an engine intake device that can adjust swirl and the like and reliably prevent abnormal combustion and reduction in combustion efficiency.

(Structure of the Invention) The present invention comprises an intake passage downstream of the throttle valve consisting of a low-load intake passage and a high-load intake passage interposed with a control valve that closes at low load, and the above-mentioned control according to the operating state. In an engine intake system equipped with a control means for controlling the opening degree of a valve, the air-fuel ratio detection means detects the air-fuel ratio of the air-fuel mixture supplied to the engine; A correction means is provided for correcting the opening degree of the control valve in accordance with the above.

In other words, not only when the operating condition changes, but also when the air-fuel ratio changes under the same operating condition, the intake flow rate, intake swirl, etc. can be adjusted appropriately by correcting the opening degree of the control valve accordingly! ! I try to do that.

(Embodiment) FIG. 1 shows an embodiment of the overall structure of the device of the present invention. In this figure, in an intake passage 3 that supplies intake air to a combustion chamber 2 formed in a cylinder 1 of an engine, a high-load intake passage 5 and a low-load intake passage 6 are formed downstream of a throttle valve 4. The downstream end of the intake passage 3 opens into the combustion chamber 2, and the opening 7 is equipped with an intake valve 8. The high-load intake passage 5 is formed with a relatively large passage area and communicates with the opening 7, and an lIJw valve 9 made of a butterfly valve or the like is interposed in the high-load intake passage 5. ing. Further, a fuel injection valve 10 for injecting fuel toward the vicinity of the opening 7 is provided on a passage wall near the intake valve 8. Furthermore, the low-load intake passage 6 has a smaller passage area than the high-load intake passage 5.
It is formed along and below the above 1iIJtI
It branches from the high-load intake passage 5 upstream of the ll valve 9, and its downstream end opens into the high-load intake passage 5 immediately upstream of the intake valve 8.

The downstream end of the low-load intake passage 6 opens in the tangential direction of the cylinder 1, and the intake air passing through the low-load intake passage 6 is supplied to the combustion chamber 2 in the circumferential direction. on the other hand,
The vicinity of the downstream end of the high-load intake passage 5 is bent or curved so as to open in the axial direction of the cylinder 1 with respect to the intake passage 3 . Therefore, the above II
When the IIIN valve 9 is closed, intake air is supplied to the combustion chamber 2 only from the low-load intake passage 6 with the high-load intake passage 5 blocked by the control valve 9, thereby increasing the intake flow velocity. At the same time, a strong intake swirl is generated in the combustion chamber 2, and when the control valve 9 is opened, intake air is supplied from the high-load intake passage 5, thereby reducing intake resistance and suppressing the intake swirl. The structure is such that the intake flow rate, intake resistance, and strength of the intake swirl are adjusted according to the opening degree of the valve 9.

The control valve 9 is controlled by a control unit 12 composed of a microcomputer etc. via an actuator 11 composed of a linear solenoid etc. so that the opening degree changes according to the operating state and the air-fuel ratio. It can be closed. The control unit 12 includes a negative pressure sensor 13 that detects the load by detecting the intake negative pressure downstream of the throttle valve 4, a rotation speed sensor 14 that detects the engine speed, and an air flow sensor that detects the amount of intake air. 15, a lean sensor (air-fuel ratio detection means) 16 that detects the air-fuel ratio of the air-fuel mixture supplied to the engine, a torque sensor 17 that detects the torque of the engine, and a throttle opening that detects the opening of the throttle valve 4. Each detection signal from the sensor 18 is input.

The control unit 12 functions as i, II@ means for controlling the opening degree of the control valve 9 according to the operating state, and also functions as a means for controlling the opening degree of the control valve 9 according to the air-fuel ratio of the air-fuel mixture supplied to the engine. The fuel injection valve 10 has a function as a correction means for correcting the temperature, and also controls the fuel injection valve 10. In other words, the control unit 12 controls the fuel injection from the fuel injection valve 10 according to the intake air port detected by the lean sensor 16, and
In addition to basic control such as controlling the opening degree of the control valve 9 according to the operating state detected by the negative pressure sensor 13 and the rotation speed sensor 14, the air-fuel ratio is varied when necessary, as will be described later. The opening degree of the control valve 9 is corrected according to the air-fuel ratio (X).

Furthermore, in this embodiment, the opening degree and ignition timing of the throttle valve 4 are also corrected according to the air-fuel ratio, and the throttle valve 4 is operated according to the operation amount of the accelerator pedal (not shown). , a throttle valve operating device 19 whose opening degree can be electrically adjusted, and an ignition device 20
is also controlled by the control unit 12.

The control unit 12 corrects the opening degree of the control valve 9 according to the air-fuel ratio as shown in FIG. Even if the air-fuel ratio deviates in either direction or rich direction, the combustion speed inherently decreases. Therefore, the opening degree of the control valve 9 is reduced to increase the intake flow velocity and the intake swirl. In addition, for example, after warm-up or when a steady state of operation continues for a predetermined period of time, it is desirable to lean the air-fuel ratio while keeping the output constant from the viewpoint of driving performance and economy. As shown in Fig. 3, the fuel flow rate, intake air amount, and control valve 9
The opening degree and ignition timing are changed. In other words, when transitioning from the stoichiometric air-fuel ratio YO to a predetermined lean state, the fuel flow rate gradually decreases and the intake air amount gradually increases to compensate for the decrease in output by increasing charging efficiency. The opening degree is gradually reduced and the ignition timing is gradually advanced to compensate for the decrease in combustion speed due to lean engine transition, and the synergistic effect of these actions prevents a decrease in output during lean transition.

Such adjustment during lean transition is performed by the torque sensor 1.
This can be done by feedback controlling the opening of the throttle valve 4, the opening of the control valve 9, and the ignition timing in the direction of suppressing torque fluctuation according to the output of the control valve 7. A specific example of this control is shown in FIG. Shown in a flowchart. In this flowchart, the pulse width of the fuel pulse output to the fuel injection valve 10 is τ, the opening degree of the throttle valve 4 is θ, the opening degree of the control valve 9 is ψ, the ignition advance angle is Ig, and their initial values ( value before lean transition) to τ0. θ0. ψo and Igo, the variables used in calculations for changing these are C1, C2, C3, and C4, and the counters are I, J, and L.

This flowchart starts when the state where the shift to the first step is to be performed, such as at the end of warm-up operation (step S1).
, initialize each counter to 1, J, and L to O in step S2, and then initialize the torque sensor 1 in step S3.
Read the output of step 7 and set it as the initial output To. Next, in step S4, the output ■ of the lean sensor 16 is read, and in step S5, the output ■ and the target air-fuel ratio V for lean transition are read.
It is checked whether the difference (IV-Vtl) with respect to t has become smaller than a predetermined minute value ε0.

When the determination result in step S5 is NO, as a process for lean transition, the counter ■ is incremented by 1, and the pulse width of the fuel pulse is set to τ [τ=τo (1-C
IXI)], that is, the pulse width τ is made smaller.

Then, by repeating the process of returning to step S4 through the processes of steps S♂ to 511i, which will be described later, step Ss is obtained.

Each time S7 is passed, the fuel injection r determined by the above pulse width τ
Decrease J4IIi by a predetermined amount.

Following steps Sa and Sy, steps 88 to S10
Now, the initial output To and current output T of the torque sensor 17
The counter J is incremented by 1 until the difference from 1 becomes smaller than a predetermined small value ε1, and the opening degree θ of the throttle valve 4 is
Repeat the process of setting [θ=θO(1+C2XJ)],
In other words, by increasing the opening degree of the throttle valve 4, the charging efficiency is increased and the torque is brought closer to the initial value. Next, in steps 811 to 813, the initial output To of the torque sensor 17 is
The counter K is incremented by 1 and the opening degree ψ of the control valve 9 is increased by [ψ−ψo (
1 - C3 Next step S++
~Sta, the difference between the initial output To of the torque sensor 17 and the current output T1 is a predetermined minute value ε3 (however, S3
S2) Adjust the ignition advance angle Io until it becomes smaller than tta.
=rGo (1+C3XL)1, that is, advance the ignition timing and return the torque to approximately its initial value.

The processing from step S4 to step S16 is repeated during the lean transition, and therefore, as the fuel injection amount gradually decreases by a predetermined amount, the opening degree of the throttle valve 4, the opening degree of the Ill III valve 9, and the ignition timing change. The torque also changes at the same time, and the torque is kept approximately constant even during the lean transition. Then, if the determination result in step S5 is YES, the lean transition ends (step Sv).

Note that although the above flowchart shows only the control during lean transition, the control of the opening degree of the control valve 9 and the like according to the normal operating state may be performed in the same manner as in the past.

As described above, when the air-fuel ratio fluctuates, the opening degree of the control valve 9 is corrected accordingly, so that the intake flow velocity, intake swirl, etc. are adjusted to match the fluctuations in the air-fuel ratio, and the air-fuel ratio This will prevent a decrease in combustion efficiency and abnormal combustion due to fluctuations in

In the above embodiment, the opening degree of the throttle valve 4 and the ignition timing are corrected in accordance with the air-fuel ratio as well as the opening degree of the control valve 9. However, if the opening degree of the control valve 9 is corrected according to the air-fuel ratio, combustion efficiency, etc. can be improved.

Further, the present invention is not limited to an engine in which the downstream end of the low-load intake passage 6 opens into the high-load intake passage 5 immediately upstream of the intake valve 8 as in the above embodiment; Both load intake passages open independently into the combustion chamber,
It can also be applied to an engine in which each opening is equipped with an intake valve.

(Effects of the Invention) As described above, the present invention appropriately adjusts the intake flow rate, intake swirl, etc. by controlling the opening degree of the control valve provided in the high-load intake passage. Since the opening degree of the control valve is corrected according to the air-fuel ratio of the air-fuel mixture, the intake flow velocity and intake swirl are adjusted to match fluctuations in the air-fuel ratio, thereby preventing a decrease in combustion efficiency or Abnormal combustion can be reliably prevented, thereby improving output and fuel efficiency.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an embodiment of the device of the present invention, Fig. 2 is an explanatory diagram of the correspondence between the air-fuel ratio and the opening of the control valve corrected accordingly, and Fig. 3 shows the An explanatory diagram showing changes in fuel flow rate, intake air ratio, control valve opening, and ignition timing when controlling the fuel ratio to shift to a lean state. Fig. 4 shows a specific example of fri control when shifting to a lean state. 3 is a flowchart showing an example. 3... Intake passage, 4... Throttle valve, 5... Intake passage for high load, 6... Intake passage for low load, 11...
・Actuator (control means and correction means), 16.
...Lean sensor (air-fuel ratio detection means). Patent applicant Mazda Co., Ltd. Agent
Patent Attorney Etsushi Kotani Patent Attorney
Long 1) Masayuki Patent Attorney Yasuo Itaya 1st Figure 2 Rikishi-9 3rd Figure Hiro*s / W □ Yuki, 77': Bakuken ゝ1ゝ＼8, Hein 111-1, - 〆

Claims (1)

[Claims] 1. The intake passage downstream of the throttle valve is composed of a low-load intake passage and a high-load intake passage in which a control valve that closes at low load is interposed, and the opening degree of the control valve is controlled according to the operating state. In an engine intake system equipped with a control means, the air-fuel ratio detection means detects the air-fuel ratio of the air-fuel mixture supplied to the engine, and the control valve receives the output of the air-fuel ratio detection means and controls the control valve according to the air-fuel ratio. An intake device for an engine, characterized in that it is provided with a correction means for correcting an opening degree.